Process for treating resins



Patented June 9, 1931 PAUL STUHLMANN, 0F COLOGNE-LINDENTHAL, GERMANY PROCESS FOR TREATING RESINS No Drawing. Application filed February 9, 1928, Serial No. 253,203, and in Germany January 24, 1927.

The invention relates to a process for treating resins. One of the principal objects of the invention is to harden dark, and even light resins, such as tree-stump resin or bal- 5 sam resin, at the same time as bleaching them.

Further objects are to provide improved processes of bleaching and/or hardening natural resins and to produce improved products therefrom.

The cheap dark resins could hitherto only be used to a limited extent, e. g. for sizing pasteboard and wrapping papers. It is possible by the invention to improve the proper ties of dark resins so that fine qualities of paper can be sized therewith. It has already been proposed to bleach dark resins by dissolving them for example in benzine and treating them with bleaching agents. A special expensiveprocess was necessary for this purpose, however, and the resinsthus purified easily turn dark subsequently.

In the process according to the present invention, the resins are dissolved in alkaline solutions and the solution is subjected to treatment therein e. g. a bleaching and hardening process. Thus the advantage is obtained that the solution of the resins required for working up to paper size and the bleaching and hardening thereof are combined in a single process.

The solution of the resin is effected in a cold dilute alkaline lye which has the advantage that only a very small portion of the resin is saponified in the cold dilute solution and it goes into solution practically entirely as free resin.

The bleaching and hardening agents can be added to the resin during solution or following thereon. The usual bleaching agents such as hydrogen peroxide, sodium perborate, and others can be used. These usual bleaching agents are used in the new process along with suitable hardening agents such as henols or aldehydes for example formaldel fyde, furfurol and the like.

It has been discovered that the dissolved resin is not only hardened by (for example) aldehyde, but is also at the same time bleached, which increases the effectiveness and the value of the resin considerably. The

other suitable bleaching agents used in addition to aldehydes, phenols and other hardening agents, serve mainly to assist the reaction. It is advantageous to include carbon dioxide or salts containing carbon dioxide, such as for example sodium bicarbonate, in the remaining bleaching agents.

A special features of the process according to the present invention is that the known additions such as water glass, animal and vegetable sizes, seaweed and etc., which are added to the resin, for example, in the manufacture of resin size for the paper industry for economical reasons, are added to the alkaline solution of resin and treated along with the latter. These additions are also favourably afiected, purified and partially bleachedin the combined solution.

An example of the process for carrying out the present invention is given herewith.

The resins, more or less finely divided and, if necessary, ground, are dissolved in the cold in a dilute alkaline lye which is kept in continuous motion by stirring mechanism, pumps, air circulation or the like. Any additional substances are also admixed with this solution.

The usual bleaching agents, for example, hydrogen peroxide, sodium perborate, or others, which can be added separately or several together, can be added to the resin solution during solution or following immediately thereon. Aldehydes, such as formaldehydes or furfurol, are added in addition to these bleaching agents, which, together with the usual bleaching agents, effect excellent bleaching or decolourization of the resin solution and also harden the resin at the same time. This bleaching and hardening process is carried out in the cold. The action can be assisted by adding phenols and other hardening agents.

It is advantageous in all cases to have carbon dioxide or salts of carbonic acid present amongst-the bleaching agents. Excellent results' are obtained, for example, when the resin is dissolved with addition of sodium bicarbonate and is bleached and hardened with formaldehyde and hydrogen peroxide,

casein vegetable substances,.

Iclaim: 1. A process for bleaching resins which consists in subjecting them in an alkaline lye in the cold with continuous movement to the common action of a bleaching agent and of formaldehyde.

2. A process for bleaching resins which consists in subjecting them in an alkaline lye in the cold with continuous movement to the common action of a bleaching agent,

and of formaldehyde in the presence of carbonic acid.

In testimony whereof, I have signed my name to this specification at Cologne, Germany, this 25 day of January, 1928.

PAUL STUHLMANN. 

